In this part of the program: America's jam packed prisons and the push in the United States Senate that could help do something about it. In a moment, we'll hear a bit about why federal prisons house more inmates than they ever have. And we'll start with news that the Senate Judiciary Committee has approved a bill that would lower mandatory sentences for some drug crimes, and would allow thousands of inmates behind bars for crack cocaine offenses to ask for early release.

NPR's Carrie Johnson was at that Capitol Hill hearing this morning and she's here now to explain what happened. Hello, Carrie.

CARRIE JOHNSON, BYLINE: Hi, Audie.

CORNISH: So there's not much that Congress can agree on these days. But the committee voted 13-to-5 to clear this bill. How did they come to compromise on drug sentences?

JOHNSON: The short answer, Audie, is a very unusual coalition of liberals and Tea Party favorites. So longtime Democrats like Richard Durbin of Illinois and Patrick Leahy of Vermont, aligned in this case with Mike Lee of Utah, Ted Cruz of Texas and Rand Paul from Kentucky. They had in essence an agreement about the role of the government and the fact that the federal government is just spending too much on housing inmates in U.S. prisons.

Three years ago, some same the same characters, Audie, got together and lowered the penalties for some crack cocaine offenses, because they cited huge racial disparities. African-American and Latino inmates were serving much longer sentences than white inmates. The goal is to do more of that now.

Here's Senator Durbin talking about his ideas.

SENATOR RICHARD DURBIN: When we enacted these penalties we wanted to go after the kingpins. If you look back, as I have, at the debate on mandatory minimums, the goal was to nail the kingpins and to break up these drug cartels. What we've learned is the laws do not sufficiently separate big time career offenders from lower level offenders.

JOHNSON: So this bill sponsored by Senator Durbin would target to non violent offenders in drug cases, people who didn't use firearms when they were committing these crimes, and who have no ties to big gangs or cartels. And Durbin's bill would allow judges to cut mandatory minimum sentences in half for a lot of these drug crimes.

CORNISH: And we should say there definitely has been some push back, right, from prosecutors and also law and order Republicans in Congress. Detail their objection.

JOHNSON: Yeah, the main concern, Audie, seems to be public safety. Violent crime has reached historic lows over the last decade or so and some federal and state prosecutors, as well as some lawmakers on Capitol Hill, are worried that if you cut back on some of these penalties, violent crime could creep back up again.

Iowa Republican Senator Charles Grassley worried today about where to draw that line.

SENATOR CHARLES GRASSLEY REPUBLICAN, IOWA: The fact is that the number of people in federal prison for simple drug possession is near zero. The supposedly non violent offenders this bill addresses are mostly drug dealers. Maybe they used no violence in committing this particular crime, but maybe their co defendants carried the gun in committing their drug offense.

JOHNSON: Essentially, Audie, with Senator Grassley is saying here is that prosecutors should be the deciders and should continue to hold the reins. And, you know, Senator Grassley did score one victory today, Audie. To the dismay of advocacy groups representing inmates, he actually got the committee to approve two new mandatory minimum sentences for domestic violence and sexual abuse offenders.

CORNISH: Now, this bill still has to pass the full Senate and get through the U.S. House. What are you hearing about the prospects for this moving forward?

JOHNSON: So a leading Republican senator today said that Republicans will not filibuster the bill when it gets to the Senate floor. It's still not going to be easy. There is bipartisan support in House but these days it's hard and can take a while for Congress to move.

There is some action outside Congress though, Audie. Today, the White House and the Justice Department seemed to open the door to entertaining more petitions for clemency and reduce sentences from inmates who are currently behind bars, serving time for drug offenses, if they were nonviolent offenders.